>The costs of maintaining a fork are quite high.
They don't have to maintain a fork, that is only 1 of the options. They can use their fork as a proxy to open PRs in github/gitlab/etc using the nostr submitted patches.
> what if they could create a repo event which highlights that they are not the maintainer
Why not just submit the repo event with an empty maintainers list? It's essentially the same thing, or not? 🤔